The present invention relates generally to inspection apparatus and, more particularly, to apparatus for inspecting crankshafts to determine if the throws thereof are within tolerance with respect to the crankshaft journal and optionally for marking the journals for turning and grinding.
U.S. Pat. No. 4,030,172 is directed to apparatus and a method for forming a multiple throw crankshaft from a metal rod in a single forming operation. Such formation defines the throws or cranks of the crankshaft and may roughly form the journal portions. After formation, the journals of the crankshaft may later be defined by grinding and polishing of the journal portions.
It is possible that a crankshaft formed by such apparatus, as well as crankshafts formed by other forming method or apparatus, could be out-of-tolerance, that is, the position of a throw from the axis of the journal portions deviating from an ideal distance by more than an acceptable amount. Such an out-of-tolerance condition could be the result of operator error, a worn or otherwise defective component in the forming apparatus, as well as other causes. Also acceptable tolerances for certain types of crankshafts can be particularly stringent. For example, the throws of a finished crankshaft formed of one and one quarter inch diameter steel rod and about six feet in length, may be required to meet tolerances of plus or minus about 0.02 inches. Heretofore, out-of-tolerance crankshafts were typically discarded, or were sometimes used for other applications where looser tolerances applied.